In:
Applied and Environmental Microbiology, American Society for Microbiology, Vol. 80, No. 7 ( 2014-04), p. 2229-2239
Abstract:
Hydrogen peroxide production is a well-known trait of many bacterial species associated with the human body. In the presence of oxygen, the probiotic lactic acid bacterium Lactobacillus johnsonii NCC 533 excretes up to 1 mM H 2 O 2 , inducing growth stagnation and cell death. Disruption of genes commonly assumed to be involved in H 2 O 2 production (e.g., pyruvate oxidase, NADH oxidase, and lactate oxidase) did not affect this. Here we describe the purification of a novel NADH-dependent flavin reductase encoded by two highly similar genes ( LJ _ 0548 and LJ _ 0549 ) that are conserved in lactobacilli belonging to the Lactobacillus acidophilus group. The genes are predicted to encode two 20-kDa proteins containing flavin mononucleotide (FMN) reductase conserved domains. Reductase activity requires FMN, flavin adenine dinucleotide (FAD), or riboflavin and is specific for NADH and not NADPH. The K m for FMN is 30 ± 8 μM, in accordance with its proposed in vivo role in H 2 O 2 production. Deletion of the encoding genes in L. johnsonii led to a 40-fold reduction of hydrogen peroxide formation. H 2 O 2 production in this mutant could only be restored by in trans complementation of both genes. Our work identifies a novel, conserved NADH-dependent flavin reductase that is prominently involved in H 2 O 2 production in L. johnsonii .
Type of Medium:
Online Resource
ISSN:
0099-2240
,
1098-5336
DOI:
10.1128/AEM.04272-13
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2014
detail.hit.zdb_id:
223011-2
detail.hit.zdb_id:
1478346-0
SSG:
12
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